Method and apparatus for quantitative determination of gases



March 30 1926.

. I S.:H. KATZ METHOD AND APPARATUS FOR QUANTITATIVE DETERMINAlTION OF GASES Filed March 12,

INVENTOR 704 j? I March 30 1926. 1,578,666 I S. H. KATZ I METHOD AND APPARATUS FOR QUANTITATIVE DETERMINATION OF GASES Filed March 12, 1925- 2 Sheets-Sheet 2 a 2 u 3 1 Vl w; W I \w v m g \||l||.|.\ rue .IZYM i) w .w. I J'J J' fi' v. v 1... 125...?!1! v u "WW I v To Z m E I If .l. I m Q WZ :3 w 4 I I E 6 l Patented Mar. 30, 1926.

UNITED. STATES PATENT OFFICE.

SIDNEY H. KATZ, .OF iPITTSBUBGH, PENNSYLVANIA.

METHOD AND APPARATUS FOR QUANTITATIVE DETERMINATION OF GASES.

Application filed March 12, 1925. Serial 1T0. 14,915.

This invention relates to a method andv apparatus for the quantitative determination of combustible gases and is particularly useful for determining the-quantity of carbon monoxide or hydrogen present in air or oxygen, although it can also be used for the quantitative determination of othergases.

The principle .of indicating the presence of combustible gases in mixture with air or oxygen by a differential temperature effect obtained when the mixture is brought into contact with a catalyst to promote oxidation is well-known. and has been used for many years. As hereto ore employed, however, the apparatus has not been as sensitive as desired and the use of such apparatus has therefore been limited. A difficulty has also been experienced with the poisoning of the catalyst, thus further materially reducing the accuracy of the apparatus and requiring frequent changes of the catalyst.

I provide for purifying the mixture by removim all ases which ma oison the catalyst and thus insure accuracy at all times. Only 'carbon monoxide, hydrogen,

methane and the normal components of air,

excepting water vapor, can pass through the purifying system. The carbon monoxide, hydrogen and methane are combustible but the methane is not affected at the temperatures employed and passes through the apparatus without change.

If hydrogen accompanies the carbon monoxide the temperature of the environment of the catalyst is important. Accord ing to the proportion of hydrogen the temperature is maintained at a higher or lower oint to cause most active oxidation of carlion monoxide compatible with reduction of oxidation of hydrogen to a negligible amount.

l furtlier provide greatly improved gas to be measured,

method of measuring the temperature increase when the mixture 1s exposed to the catalyst, and am thus enabledto measure exceedingly minute quantities of such gases as carbon monoxide in air. The apparatus is therefore exceedingly useful in the determ nation of CG content in tunnel gases and the like.

I also provide for operating the apparatus at the best flow rate for measuring the gas concentration. Experiments show that if the temperature increase is measured by a thermocouple system and the flow rate be plotted against the potential for any concentration, the potential rises quite sharply with the rate of flow until a maximum is reached, after which the potential falls oil rather more slowly. Tests with gases of various concentrations show that these maxima occur at substantially the same rate of flow, and that the rapidity of response of the apparatus to varying concentration is more rapid at this flow. I therefore provide for supplying gas to the measuring apparatus at this flow rate, thus securing the maximum potential for any concentration of gas. This is conducive toward greatly increased accuracy in measuring the concentration of CO or other gas being measured.

I prov de a plurality of thermocouples arranged in series for measuring the temperature increase occasioned by passing the gas mixture over the catalyst. TlllS arrange- 'ment greatly increases the potential and is conducive to highly accurate readings. The combination of these several features provides an apparatus which in practice has been found capable of measuring extremely low percentages of carbon monoxide. -The device has been successfully used to measure concentrations up to of CO and it is therefore useful in commercial applications such as measuring the CO content of stack gases from boiler furnaces or other combustion furnaces. When it is to be used for the quantitative determination of gases which are very rich in carbon monoxide or other as for example blast furnace gas, the apparatus may-be used'by known proportion of air,

carbon monoxide and with the temperature of the catalyst at about 100 C., is not materially affected by hydrogen in partial volume equal to or less than the carbon monoxide because the hydrogen is so much more slowly affected by the catalyst.

Thus hydrogen in the proportions usually present in automobile exhaust gases or flue gases from furnaces, causes a negligible error in the indications of the CO. 011 the other hand by reducing the rate of fiow through the catalyst to about one-fifth of the best rate for carbon monoxide, the best rate for hydrogen is obtained. The effect of the hydrogen in the potentials is increased many fold and the apparatus may, in absence of carbon monoxide or removal of carbon monoxide by selective oxidation be used to indicate hydrogen. Reducing the temperature of the gases brought to the catalyst and the environment of the catalytic cell to 25 C., eliminates entirely any thermoelectric effect due to hydrogen but does not materially reduce the effect of carbon monoxide. Hence by operating in a low temperature environment carbon monoxide can be determined in mixture with any large amounts of hydrogen. Both CO and hydrogen may be determined in a single gas by first determining the CO in a cell at low temperature, then after complete selective oxidation of the CO to CO passing the gas through a cell at higher temperature to 1 termine the hydrogen.

In the accompanying drawings illustrating thepresent preferred embodiment of my invention Figure 1 is a diagrammatic view of an apparatus embodying my invention;

Figure 2 is a vertical section through a portion of the apparatus of Figure 1 showing the chamber containing the thermocouples and the catalyst;

Figures 3 and 4 are side and end views. respectively of the thermocouples employed;

Figure 5 is a die am showing the relation between potential and rate of flow for various gas concentrations; and

Figure 6 is a diagrammatic View of a modified apparatus.

In the illustrated embodiment of the in.

vention there is shown a supply line 2 through whichthe gas mixture to be tested is drawn by a motor operated pump 3. The gas passes from the pump 3 through a conduit 4 into a series of bottles 5, 6, 7 and 8.' A discharge pipe 9 provided with a valve 10 is connected in the conduit 4 so that, excess gas drawn by the pump or blower may be discharged from the ap aratus. The hottles 6 and 7 are wash bott escontaining su lphuric acid. The acid dries the ases and also removes ammonia and certain hydrocarbons and gases soluble in 'or retai ed by notaecc sulphuric acid. The bottles 5 and 8 serve as traps to prevent passage of acid to other parts of the apparatus. From the bottle 8 the washed and dried gas passes through a conduit 11 in which a calibrated manometer 14 for indicatin the j rate of flow. Connected to the conduit 11 just ahead of the flow meter 13 is a tube 15 extending downwardly into a well 16. The well 16 is open tothe atmosphere at 17 and the arrangement provides an escape for gas from the conduit 11 as long as the pressure inside the conduit exceeds the hydrostatic pressure at the bottom'of the tube 15. The flow of gas may be regulated byadjusting the depth to which the tube 15 is immersed in the well 16.

The gas passes from the flow meter 13 through a conduit 18 and connected to this conduit 18 is a pipe 19 communicating with a water reservoir 20. The reservoir 20 is connected to the bottom of the well 16 by a conduit 21 and the apparatus is effective for maintaining a constant rate of flow of gasregardless'of the resistance of the succeeding parts of the apparatus. This is accomplished by varying automatically and equivalently the depth of the water in the well 16 as the pressure in the apparatus varies due to any variation in resistance beyond the flow meter 13. A constant pressure difference is thus maintained across.

the orificein the flow meter.

The gasv passes through the conduit 18 ated steam at atmospheric pressure, the

water bein heated by a Bunsen burner. The bath is provided with a reflux condenser 26, the vent through which maintains atmospheric pressure in the steam bath and thus provides a constant temperature.

The gas as-it passes through the co l 24 is heated to steam temperature and then passes through a conduit 27 into the chainher 28 containing'the catalyst and the thermocouples for measuring the evolved heat.

This app ratus is shown in detai i Figure 2 and comprises an inner cell 29 having openings 30 at top and bottom covered with screens or gratings 31. Side walls 32 within the cell 29 provide a space which contains the thermocouples and the catalyst.

The loweiuportion of this space is filled with granular pumice stone 33 and the upper portion is filled with a suitable catalyst 34, I prefer to use hopcalite, a specially prepared mixture of man'ranese dioxide with basic copper carbonatefas thecatalyst. This catalyst causes the union of any carbon monoxide present with the oxygen in the air, thus bringing about a temperature in-- crease which is a measure of the amount of CO present. The gases are wasfiedthrough the guard tube 42containing fused calcium chloride to prevent entrance of moisture.

The temperature increase is preferably.

. line in Figures 3 and 4. The cold junctions are at 36 and it will be seen that they lie in the pumice stone while the hot junctions are at 37 surrounded by the hopcalite. The cold junctions 36 will therefore, be maintained at the entrance temperature of the gas while the hot junctions willbe at'a higher temperature determined by the amount of heat evolved when the mixture comes in contact with the catalyst. If desired, the ends of the thermocouple: wires at the respective junctions may extend away from the cards to insure better contact by the gases and lead heat to or from the junctions. Lead wires 38 connect the apparatus with any suitable indicating or recording mechanism.

In Figure 1 there is shown a recording instrument 39 adapted to continuously record upon the line chart 40 the amount of CO present in the mixture. There is also shown-a bell 41 connected to the recording mechanism 39 and arranged to ring and thus indicate a maximum CO content. It will be understood that- 1f desired the apparatus may be. connected to control mechanism for operating fans or dampers to vary the air supply and thus bring conditions back to a desired normal.-

The apparatus above described is effective for supplying washed and purified gas at constant temperature. to the catalyst and at any desired rate. I have found that there is a best flow rate at which the apparatus should be operated if most accurate results are to be obtained and particularly if it is desired to record the results upon a suitable calibrated chart.

Figure 5 shows the indicated potential 1 plotted against the rate of flow for different gas concentrations. The solid lines Show the hydrogen curves, and the chain lines show the CO curves. It will be noted that in each case the curve rises rather sharply up to a maximum and then drops off more slowly. It will also be noted that the peaks of the several hydrogen curyes lie substantially in a vertical line indicated at X and that thepeaks of the CO curves are similarly related, all of them lying in the line X I prefer to operate the apparatus at the 0ptimum flow rate thus shown in order to secure the maximum potential for any gas concentration, since this is most conclusive to accurate reading.

It is clear from Figure 5-tl1at if the ap-' paratus is operated at the best flow rate for CO the oxidiation of hydrogen will be relatively small. I have found, however, that it is highly desirable to properly regulate the temperature of the gas and the hopcalite when it is desired to make a quantitatlvedetermination of a gas containing both CO and H By proper temperature regulation the amount of each of the gases present may be very accurately determined.

Figure 6 shows a form of apparatus for the quantitative analysis of CO and H mixed with air or oxygen. In using this apparatus thewashed and dried gas is supplied through a conduit 23*to a coil 24 and a catalytic cell 28". Both of these are, with-.

in a container 25", having anydesired heating and heat controlling means, indicated at The container 25 is maintained at sub-' (not shown) similar to that illustrated in Figure 1. v

The gas leaves the cell 28' through a conduit 44. It passes to a coil 24* and a cell '28 contained in a container 25 and provided with thermostatic temperature controller 43". The cell 28". is preferably maintained. at substantially the same temperature as the cell 25. It is not provided with any temperatureindicatingmeans', as its function is merely to cause oxidation of any (30' remaining in the gas after it passes through the cell 28. It, will be understood that while H will not be oxidized at a low temperature such as 25 C.', the CO- will be. oxidized at a temperature such as is required to oxidize H or higher. The cell 28" is therefore valuable for example, C.

in that it removes the CO remaining in the gas andmakes for an accurate H reading. The cell should be of relatively large size in grler to effectively remove the remaining From the cell 28 the gas passes through a conduit 45 to a coil 24 and a cell 28, both contained in a jacket 25. The jacket is provided with a thermostatic temperature controlling means 43 and this is adjusted to maintain a temperature conducive to the oxidation of the H content. A temperature of 100 C. or higher is satisfactory and may be easily maintained by a steam bath. I

The apparatus in the forms illustrated may be used to determine the amount of CO present in air or oxygen whether H is present or not. It may also be used for determining theamount of H in air or oxygen, whether CO is present or not, and with the apparatus shown in Figure 6 the amount of each gas present may be determined. I

The sensitivity of the apparatus may be regulated as desired by the number of thermocouples employed, and it is preferred to use a large number. By using a suitable number of thermocouples and by operating the apparatus at the best flow rate, as indicated in Figure 5, concentration as low as one part permillion may be measured and recorded. An apparatus comprising 48 couples determining CO in an environment of 100 C. has been found to have a best flow rate of 46 liters per minute. Another of 96 couples required 85 liters per minute. I thus provide a method and apparatus for quantitative determination of gases in which the gases are purified and passed over a catalyst at a constant optimum tempera.- ture and constant pressure and at a desired flow rate. The provision of :a. plurality of thermocouples in series for measuring the evolved heat insures highly accurate readings and this, in combination with the supplying of gas to the apparatus at a rate substantially equivalent to the rate corresponding to maximum temperature increase for any gas concentration, makes it possible to lieasure exceedingly minute proportions of The use of hopcalite as a catalyst for carbon monoxide is particularly desirable since hopcalite when used with suitable temper atures and rate of flow is affected only very slightly or not at all by the presence of hydrogen. The apparatus will therefore measure the 00 content of a gas and the presence of hydrogen inv quantities up to the equivalent volume per cent of the carbon monoxide does. not cause appreciable error. The apparatus may be operated at ordinary room temperatures and as far as carbon monoxide isconcerned the provision of the steam bath inwhich the cell is placed is largely a matter of convenience for obtaining a uniform temperature of the gas. In fact, operation at room temperatures enables analysis of small proportions of carbon monoxide in Very large proportions of hydrogen. By reducing the rate of flowfrom the bes rate for carbon monoxide and maintaining steam temperatures, the apparatus can made to record hydrogen when carbon monoxide is absent or has been eliminated. It may thus be very useful in processes for synthetic production of ammonia. As will be seen from Figure 2, the'catalyst chamber is exceedingly well insulated so that the po tenti-al set up in the lead wires is a true measure of "the'evolved heat. The apparatus is therefore capable of much more accurate and delicate determinations than have heretofore been considered possible with apparatus of this character. At the same time the advantages of rapid detern'iination are increased largely and none of the advantages of simplicity of apparatus are lost. This is particularly true in view of the provision for purifyingthe gas, thus preventing vapors in air or oxygen, and may be other-' wise embodied within the scope of the following claims.

I claim:

1. The method of quantitative determination of gases, which includes subjecting the gas to the action of activated charcoal, passingthe gas over a catalyst and measuring the resulting temperature increase.

2. The method of quantitative determination of gases, whichincludes drying the gas with sulphuric acid, subjecting the gas to the action of activatedcharcoal, passing the gas over a. catalyst and measuring the resulting temperature increase.

3. v The method of quantitative determination of gases, which includes subjecting the gas to the action of activated charcoal and a caustic substance, passing the gas over a catalyst and measuring the resulting temperature increase.

' 4. The method of quantitative determination of carbon monoxide, which includes subjecting the gas to the action of activated charcoal and a caustic substance, drying the gas, passing the gas over a catalyst and measuring the resulting temperature increase.

i 5. The method of quantitative determinathe resulting temperature increase.

.-ing the temperature increase,

' nation of carbon monoxide,

subjecting the gas to 7. The method of quantitativedetermination of gases, which includes preliminarily drying the gas, subjecting the gas to the action of activated charcoal and a caustic material, filtering thegas, again subjecting the gas to the action of a drier, passing the gas over a catalyst and measuring the resulting temperature increase.

8. The method of quantitative determination of carbon monoxide, which includes subjecting the gas to the action of a purifier,

' passing the gas over hopcalite and measuring the temperature increase, the purifier being adapted to remove gasestending to poison the hopcalite.

9. The method of quantitative determination of carbon 'monoxide, which includes the action of a filter, hopcalite and measurthe filter being adapted to remove suspensoids tending assin the 21S CV91 Y to poison the hopcalite.

= 10. The method of quantitative determi- Which includes subjecting the gas to activated charcoal and hopca-lite and measuring a caustic substance, drying the gas, passing the gas over hopcalite and measuring. the resulting temperature increase. V j 11. The method of quantitative determination of gases, which includes subjecting the gas to sulphuric acid, subjecting the gas to activated charcoal and a caustic material, filtering the gas, subjecting the gas tQfIKGCl calcium chloride, passing the gas over the resulting temperature increase.

12. The method of quantitative determi nation of a plurality of combustible gases in a mixture containing oxygen which includes supplying the mixture to a catalyst at a relatively low temperature to cause oxidation of one of said combustible gases, measuring the resulting temperature increase, thereafter supplying the mixture to a catalyst at a relatively higher temperature to. cause oxidation of another of said combustible gases, and measuring the resulting temperature increase.

13. The method of quantitative determination of a plurality of combustible gases in a mixture containing oxygen, eludes subjecting the-gas to the action of'a.

to a catalyst at a at a relatively a mixture containing oxygen,

which ingases, measuring the resulting temperature increase, thereafter supplying the mixture relatively higher temperature to cause oxidation of another of said combustible gases, and measuring the resulting temperature increase, the purifier being adapted to remove gases tending to poison the catalyst.

14. The method of quantitative determination of a plurality of combustible gases in a mixture containing,oxygemdrying the mixture, subjecting the mixture to the action of a purifier at a relatively low temperature. .to cause oxidation of one of said combustible gases, measuring the resulting temperature increase, thereafter supplying the mixture to a catalyst at a -relatively higher temperature to cause oxidation of another of said combustible gases, and measuring the resulting temperature increase, the purifier being adapted to remove gases tending to poison the catalyst. a i 15. The method of quantitative determination of CO and H in air or oxygen, which includes supplying the mixture to a catalyst low temperature to cause oxidation of the CO, measuring the resulting temperature increase, thereafter subject'- ing the remainder of the mixture'to a catalyst at a relatively higher temperature to cause oxidation of the H and, measuring the resulting temperature increase. 16. The method of quantitative'dete'rmination of a plurality of combustible gases in which includes supplying the mixture to a catalyst at arelatively low temperature to cause oxidation of at least a portion of one of said con1- bustible gases, thereafter removing from the mixture any of said gas remaining in the mixture, thereafter supplying the remainder of the mixture to a catalyst at a relatively higher temperature to cause oxidation of an other ofsaid combustible gases, and measuringthe resulting temperature increase.

17 Apparatus for determinations of gases, including a catalyst, means for passing gas thereover and a plumaking quantitative rality of thermocouples in series each having a substantially'constant temperature and a plurality of thermocouples in series each having one junction in the catalyst and the other junction out of the catalyst'but in'flie path of the gases. j J 19. Apparatus for the quantitative'determination of carbon monoxide, including a qu'antjty of hopcalite, means for supplying gas thereto, means for measuring the temperature increase, means for. subjecting the gas supplied to the hopcalite to activated charcoal and a caustic substance, and means for drying the gas.

20. Apparatus for the quantitative determination of two or more gases, includin a" plurality of catalytic bodies adapted to eii ect a chemical change, means for supplying a gaseous mixture to the catalytic bodies successively, and means for measuring the resulting temperature change at each ofsaid catalysts.

21. Apparatusfor the quantitative deter-- minationof two or more gases, including a plurality of catalytic bodies adapted to efi'ect a chemical change, means for supplying a gaseous mixture to the catalytic bodies successively, means for maintaining one catalytic body at a different temperature than at another of such bodies, and means for measuring the temperature change at each of said catalysts when the gas is supplied there- 22. The method of quantitative determination of two or more gases, which includes supplying a gaseous mixture to a catalytic body adapted to effect a chemical change, then sup lying the same gas to another catalytic bo y adapted to effect a chemical ;change,and measuring the resulting temperature change at each of said catalysts.

'23. The method of quantitative determination of ases, which includes subjecting the gas to t e action of a purifier, passing the over an oxidizing catalyst, utilizing a recording the sensitive instrument to measure the resulting temperature change, and substantially con tinuously and automatically recording the readings of said sensitive instrument, the urifier being adapted to remove gases tendmgto vitiate the analysis. 24. The method ,of quantitative determination of gases, which includes drying and purifying thegas to remove substances therefrom which would tend to vitiate the analysis, passing theg'asover an oxidizing catalyst, utilizing a sensitive instrument to measme the resulting temperature change, and substantially continuously and automatically readings of said sensitive instrument. y a

25. The methodbf quantitative determina. :tion of gases,whieh includes purifying the 'gas tol remove therefrom substances which would tend to vitiate the-analysis, passing the gas over an oxidizing catalyst,- utilizing a sensitive instrument toLmeasute theresulting temperature change, substantially "continuously and. automatically recording thereadings of said sensitive instrument, and actuating a warning signal when a predetermined condition of the' gas being analyzed occurs. i

26..The method of. quant tative determination of gases, which includes mixing the gas to be analyzed with a. known proportion of a diluting gas, passing the mixture over a catalyst, the diluting" gas being inert with respect to the catalyst, and utilizing a sensitive instrument to measure the temperature change. 27. The method of quantitative determinationof carbon monoxide, which includes diluting the gas containing carbon monoxide with air, the air being in known quantity and in such amount as to reduce the resulting carbon monoxide concentration in the mixture to not more than about one-half of one per cent,.passing the nnxtureover hopcahte, and utilizing a sensltive instrument to measure the resulting temperature change.

28. The'method of quantitative determi nation of gases, which includes subjecting the gas to a catalyst to secure a measurable temperature change, and supplying the gas to the catalyst at a rate of fiow generally equivalent to the rate -of flow at which a peak is secured on a curve in which rate of flow is plotted against temperature change.

29. The method of quantitative determination of gases, which includes subjecting the gas to a catalyst to secure a measurable temperature change, supplying the gas to the catalyst at a rate of flow generally equivalent to the rate of flow at whicha peak is securedon a curve in which rate of flow peak is secured on a curve in which a rate of flow is plotted against temperature change. 7

31. The method of quantitative determination of gases which includes subjecting the gas to a catalyst atsubstantially the best rate for the production of a measurable temperature change, that is to say, at substantially the rate vat which a maximum temperature increase is occasioned regards less. of the gas concentration, and utilizing the temperature change as a measure 'of'the concentration.

nation of gases, which includes purifying the gas, subjecting it to a catalyst at sub stantially the best rate for the productionof a measurable temperature change, that is to say, substantially the rate at which a maximum temperature increase is occa- 32. The method of quantitative determi- Y lac ' uring the,

' constant flow device the catalytic cell.

sioned regardless of the gas concentration,-

and utilizing the temperature change as a measure of the concentra ion, the-purifying stepbei-ng effective for the removal of substances tending to vitiatethe analyses.

83. The method of quantitative determination of two ormoregases, which includes supplying the gases 'to a catalytic body adapted to effect a chemical change and maintaining the catalytic body at a desired temperature, applying the same gas after it leaves the first. catalytic body'to a Second catalytic body, maintaining the second catalytic body at a different temperature,

" and, measuring the resulting temperature change at each of said catalysts.

34 Ap aratus for quantitative determination 0 gases, including a gas washer, a trap for reducing the possibility of liquid being carried over from the gas washer, a for regulating the flow of gas through the apparatus, a secondary drier adapted to remove moisture entrained in the passage of gas'through the ap aratus, and a catalytic cell having electrica means for measuring the temperature change in the catalytic cell. 7

35. Apparatus for the quantitative determinat-ioni of gases, inc uding purifying means, acatalytic cell containing an oxidizing catalyst, the purifying means being adapted to remove substances tending to vitiatethe analysis, electrical means for meastemperature change in the catalytic cell, a discharge conduit leading from catalytic cell, and means for preventing the entrance of deleterious gases or vapors through the discharge conduit to 36. Apparatus for the quantitative determination of gases, including gas supply means, a caustic material, activated charcoal and a filter in the .path of the gas, a drier, a catalytic cell containing a catalyst, and a thermocouple in said cell for determining the temperature increase in the cell.

37. Apparatus for the quantitative deter- .mination' of gases, including gassupply means, a drier, a purifier, a constant term perature chamber containing preheating means for bringing the gas'being. analyzedmeans for era-tively connecte up to substantially the temperature of the I couple within the-cell for determining the temperature increase in the cell.

'38. Apparatusfor the quantitative determination of gases, including gas supply means, a drier, a purifier, a constant temperature chamber containing preheating bringing the gas being analyzed up to substantially the temperature of the chamber, a catalytic cell within the chamber having a catalyst therein, and electrical temperature measuring means for measuring the evolved lheat.

39. Apparatus for the quantitative determination of gases, including gas supply means, a gas washer, a trap adapted to reduce the tendency of-liquid to pass over from the gas washer, a caustic material, a'filter and. a quantity of activated charcoal in the path of the as, a constant flow device for regulating te rate at which gas passes through the apparatus and a flow meter for measuringthe same, a drier adapted to remove moisture entrained in the passage of the gas through the apparatus, a constant temperature chamber, a heating coil therein adapted for bringing the gas to substantially the chamber temperature, a catalytic cell within. the chamber and electrical'temperature measuring and recording means operatively connected with the catalytic cell.

40. Apparatus for the uantitative determination of gases, inclu in gas supply means, a gas washer, a trap a apted to reduce the tendency of liquid to pass over from the gas washer, a caustic material, a filter and a quantity of activated charcoal in the path of the gas, a drier adapted. to remove moisture entrained in the'pa'ssage of the gas through the apparatus, a constant temperaturemhamber, a heating coil therein ada ted for bringing the gas to substant-ia y the chamber temperature, a catalytic cell within the chamber, and electrical temperature measurin and recording means 0 with the'catalytic, ce 1.

In testimony whereof I have hereunto set my hand. I

' SIDNEY H. KATZ. 

